Oviraptorosauria
Oviraptorosauria, (o·vi·rap·tor·o·saur·i·a meaning 'egg thief lizards', is a group of bipedal theropod dinosaurs within the Saurischia order of Dinosauria. Oviraptorosaurs are characterized by their common short skulls, which feature parrot-like beaks, as well as their common trait of feathered hides, rather than scales. The group is particularly close in evolutionary terms to that of modern day birds, and have been suggested to represent a primitive example of flightless birds. General Description Physiology Unlike other maniraptorans, oviraptorosaurs have shortened snouts with beaked jaws. Such shape gives an apparent similarity to modern day parrots. Some oviraptorosars had bony crests atop their skulls, while a few primitive examples of the group had a few teeth in the front of their mouths. In contrast to the tiny skulls present in oviraptorosaur species, the species had typically short tails that thickened at the base. The arms of the animals were long in relation to the rest of the form, and had an accompanying massive should girdle, which would have aided in the development of strong arm muscles. There are several pieces of evidence to support the claim that oviraptorosaurs were, in fact, feathered dinosaurs. Two species of primitive oviraptorosaurs have been discovered to have impressions of developed features in their fossil records, specifically located on the wings and tail of the creature. Such evidence suggests the animals at least partly used such feathers for display. A preserved skeleton of the oviraptorosaur Nomingia was found to have a tail that ended in something similar to a pygostyle, which is a bony structure used by modern birds to support a fan of feathers. Anchor points for feathers, known as quill knobs, have also been discovered on the oviraptorosaur species Avimimus portentosus. Nesting locations discovered have also been shown to depict a number of oviraptorosaur species in a nesting configuration similar to modern birds, in that that arms of the preserved specimens are positioned in such a way that they would have been able to adequately covered their eggs if they had a covering of feathers. Diet The particular details of the eating habits of the oviraptorosaurs has not been conclusively proven, as it has been suggested that the species could be anything from carnivorous to herbivorous to omnivorous. The nomenclature of the group represents the initial theory that the creatures' diet consisted of eggs stolen from other dinosaurs' nesting areas, but this theory is no longer considered valid. Oviraptor remains were discovered in Mongolia on top of a nest, which led many to speculate that the creatures were egg raiders. However, it has recently been concluded that this particular animal was on top of its own nest at the time of its death. It has also been suggested that the animals fed on mollusks, or small vertebrates. The latter theory has received partial support from the discovery of a lizard skeleton preserved in the body cavity of an Oviraptor. Two infant troodontid skulls were also discovered at a Citipati nest, suggesting the animals fed on the infants. Support for the theory that the creatures were herbivorous by nature includes the discovery of gastroliths preserved within a Caudipteryx skeleton. Classification Relationship to birds Oviraptorosaurs are so remarkably similar to birds, that some scientists have posited the theory that the species may in fact be true birds, and are more advanced than the Archaeopteryx. Some scientists have even gone as far as to include oviraptorosaurs as an order within the Avian class. However, numerous other researchers disagree with this sentiment, and believe that the oviraptorosaurs are simply a maniraptoran species slightly more primitive than the dromaeosaurs. Taxonomy * Infraorder Oviraptorosauria ** Incisivosaurus ** Protarchaeopteryx ** Family Avimimidae *** Avimimus ** '''Family Caudipteridae' *** Caudipteryx *** ''Similicaudipteryx ** '''Superfamily Caenagnathoidea' *** Hagryphus *** Family Caenagnathidae **** Caenagnathasia **** Chirostenotes **** Elmisaurus **** ?Nomingia **** ''Anzu'' *** Family Oviraptoridae **** Gigantoraptor **** Microvenator **** Shixinggia **** Subfamily Ingeniinae ***** Conchoraptor ***** Heyuannia ***** "Ingenia" ***** Khaan **** Subfamily Oviraptorinae ***** Citipati ***** Nemegtomaia ***** Oviraptor ***** Rinchenia Phylogeny |label2=Caenagnathoidea |2= }} }} |label3=Ingeniinae |3= |label2=unnamed |2= }} }} }} }} }} }} Category:Saurischia Category:Dinosaur Classification Category:Cretaceous dinosaurs